James,

Only from what I've read (no practical experience of this problem), it can
be caused by an inappropriate solder mask, especially if you're wave
soldering after CR. Which solder mask are you  using? Is your problem a
regular feature, and does it occur on all chip components or just some (is
there a pattern)? What processes are you using? Is the board double sided?

Regards

Pete Duncan



                    "Marsico, James"
                    <James.Marsico@D        To:     [log in to unmask]
                    P.AIL.COM>              cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
                    Sent by: TechNet        Subject:     [TN] soldr balls
                    <[log in to unmask]
                    >


                    08/15/01 03:34
                    AM
                    Please respond
                    to "TechNet
                    E-Mail Forum.";
                    Please respond
                    to "Marsico,
                    James"






Here's a relatively basic SMT question, but we've haven't experienced this
before.  We're seeing solder balls under (way under, in the center) chip
components.  Any recommendations?

Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879

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